Hexachloroethane (perchloroethane) is an
organochlorine compound
Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The chloroalkane class (alkanes with one or more hydrogens substituted ...
with the
chemical formula
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...
. Its structure is . It is a white or colorless solid at room temperature with a
camphor
Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel (''Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the kapu ...
-like odor.
It has been used by the military in
smoke compositions, such as base-eject
smoke munitions (
smoke grenades).
Hexachloroethane was discovered along with
carbon tetrachloride
Carbon tetrachloride, also known by many other names (such as carbon tet for short and tetrachloromethane, also IUPAC nomenclature of inorganic chemistry, recognised by the IUPAC), is a chemical compound with the chemical formula CCl4. It is a n ...
by
Michael Faraday
Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic inducti ...
in 1820. Faraday obtained it by chlorinating
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
.
Manufacture
Chlorination of
tetrachloroethylene
Tetrachloroethylene, also known as perchloroethylene or under the systematic name tetrachloroethene, and abbreviations such as perc (or PERC), and PCE, is a chlorocarbon with the formula . It is a non-flammable, stable, colorless and heavy liqu ...
at 100–140 °C with the presence of
iron(III) chloride
Iron(III) chloride describes the inorganic compounds with the formula (H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated f ...
is the most commonly used commercial production method, however several other methods exist. A high purity form can be produced in a small scale by reacting chlorine together with
barium carbide.
In September 1997, it was reported as no longer being produced in the United States for commercial distribution, but was produced as a by-product of industrial chlorination process.
:
Applications
Hexachloroethane has been used in the formulation of extreme pressure
lubricants
A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces ...
. It has also been used as a
chain transfer agent in the
emulsion polymerization
In polymer chemistry, emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomers, and surfactants. The most common type of emulsion polymerization is an oil-in-water emulsion, in ...
of propylene–tetrafluoroethylene copolymer. Hexachloroethane has been used as an
anthelmintic
Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them without causing significant damage to the host. They may also ...
in
veterinary medicine
Veterinary medicine is the branch of medicine that deals with the prevention, management, medical diagnosis, diagnosis, and treatment of disease, disorder, and injury in non-human animals. The scope of veterinary medicine is wide, covering all a ...
(under the tradename ''Avlothane''), a rubber accelerator, a component of fungicidal and insecticidal formulations as well as a moth repellant and a plasticizer for cellulose esters.
[
Hexachloroethane has been used in the manufacture of degassing pellets to remove hydrogen gas bubbles from molten aluminum in aluminum foundries. This use, as well as similar uses in ]magnesium
Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...
, is being phased out in the European Union
The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...
.
Use as smoke agent
Smoke grenades, called hexachloroethane smoke or HC smoke, utilize a mixture containing roughly equal parts of hexachloroethane and zinc oxide
Zinc oxide is an inorganic compound with the Chemical formula, formula . It is a white powder which is insoluble in water. ZnO is used as an additive in numerous materials and products including cosmetics, Zinc metabolism, food supplements, rubbe ...
and approximately 6% granular aluminium
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...
. These smokes are toxic, which is attributed to the production of zinc chloride
Zinc chloride is an Inorganic chemistry, inorganic chemical compound with the chemical formula, formula ZnCl2·''n''H2O, with ''n'' ranging from 0 to 4.5, forming water of hydration, hydrates. Zinc chloride, anhydrous and its hydrates, are colo ...
(). According to Steinritz et al., "Due to its potential pulmonary toxicity," zinc chloride producing smoke grenades "have been discharged from the armory of most western countries (...)."
Use as a riot control agent
Most documented uses of HC smoke as a riot control agent have occurred in the United States; its purchase towards that end has occurred in Milwaukee, Denver and Portland.
Federal Protective Services (FPS) and forces from the Department of Homeland Security
The United States Department of Homeland Security (DHS) is the U.S. federal executive department responsible for public security, roughly comparable to the interior, home, or public security ministries in other countries. Its missions invol ...
are believed to have used HC smoke grenades against protesters during various protests in 2020. At the time, journalists photographed numerous smoke canisters labeled "HC", and measured unusually high levels of zinc and chloride in the area. However, FPS communications director Rob Sperling has denied the use of HC smoke, arguing that, of the two organizations, "FPS doesn't have any items that contain HC."
Toxicity
Hexachloroethane is not particularly toxic when taken orally, but is considered to be quite toxic by skin adsorption. The primary effect is depression of the central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
.[ The concentration that is ]immediately dangerous to life or health
The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent adver ...
is 300 ppm and the permissible exposure limit
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agents such as high level noise. Permissible exposure limits were established by the Occupational ...
according to the Occupational Safety and Health Administration
The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...
is 1 ppm (skin).[ It is reasonably anticipated to be a carcinogen.]
References
External links
US Government Agency for Toxic Substances and Disease Registry ToxFAQs for Hexachloroethane
Scorecard.org chemical profile
US EPA Hexachloroethane fact sheet
{{Chlorides
Chloroalkanes
IARC Group 2B carcinogens
Perchlorocarbons